It may be too early to write the obituary for frequent-flier mileage runs — those legendary year-end flights that offer a shortcut to an airline's coveted "elite" status — but it's easy to see the end from here.

With Delta Air Lines and United Airlines tightening their loyalty program rules in 2014 to require more spending in order to get singled out for special treatment, many of these frivolous round trips could vanish after this winter.

"With the new revenue requirements in place, mileage running will rarely make economic sense, except in cases where a traveler is just a few miles and dollars short of an elite threshold," says Tim Winship, publisher of FrequentFlier.com.

I'll miss the mileage runners when they disappear, although I wouldn't be surprised to see more of them in the short term as they try ever more desperately to game the system.

Runners are the last true believers, chasing a dream that airlines can offer first-rate service at a reasonable price. Many also naively think they're the airlines' best friends, driven by a conviction that the "free" miles they've earned are the ultimate gauge of their loyalty, and that the allegiance will be repaid by a grateful airline.

But mostly, I'll miss mileage runners for what they did: bring out the best even in airlines known for despising their customers.

Girish Ganesan, a partner for a Santa Fe, N.M., investment management firm, is skipping the mileage run this year. The numbers just didn't add up, even though his preferred carrier offered to double his miles and grant him gold status if he takes a flight to nowhere.

Ganesan did a little research and learned that his carrier was cutting service to his closest international airport, Los Angeles.

"I checked some of the times I might want to use an award ticket, and there was one preferred date for which there was a wait list — the rest were not available," he says. "The value of the miles is practically zero for me. I would rather go at the best time for me and not worry about this offer."

In the future, something tells me the only passengers you'll find in first class are the high rollers who pay top dollar for their walk-up fares, and the loyalty-program fans who spend a ridiculous amount of time learning all the ins and outs of a program to stay a step ahead of the masses.

But it isn't only the herd of elites that's being culled next year.

The number of passengers who think their loyalty will be returned with loyalty is dwindling, too, as a new reality sets in. Starting Jan. 1, you'll have to either spend $12,500 annually with Delta and fly 125,000 miles or spend $25,000 on a co-branded credit card. United's new requirements are similar, except that you can't spend your way to a top-tier elite level on a card. Winship estimates that between 10% and 20% fewer travelers will qualify for elite status.

They're passengers such as Dave Vanderhoof, who recently retired after earning elite status on United every year for the last decade. He fondly remembers the days of end-of-year runs that resulted in liberal upgrades for the next 12 months. For him, the run was a token of his fealty to the airline, which was reciprocated with VIP treatment. But after he retired and United revised its loyalty program, "service went into the toilet," and Vanderhoof split with his preferred airline.

He no longer believes being loyal to an airline will automatically make it loyal to him. Now, he looks for a simpler proposition: a carrier that offers good service with no strings attached.

"I've switched to Virgin America," he says. "Boy, what a difference in quality and service. And I really don't care about earning rewards."

As an unapologetic critic of loyalty programs, I'm pleased that Vanderhoof and others have seen the light, but I also fear a darker future.

With fewer mileage runners out there — with fewer elites, probably — airlines will try to groom an ever smaller group of "special" customers. The result? More exclusive and spectacular first-class sections featuring lie-flat seats, even on domestic routes (JetBlue, I'm lookin' at you) and more fawning service for a select few. But in the back of the plane, look for less legroom, more maddening junk fees and flight attendants with a "you get what you pay for" attitude.